Biocidal compositions containing 4, 5-dicyano-1, 3-dithiole-2-thione oxide



United States Patent Ofilice 3,318,767 Patented May 9, 1967 3,318,767BIOCIDAL COMPOSITIONS CONTAINING 4,5-DI. CYANO-1,3-DITHIOLlE-2-THIUNEDXIDE Erwin Klingsberg, Mountainside, NJ., assignor to American CyanamidCompany, Stamford, Comm, a corporation of Maine No Drawing. Originalapplication June 26, 1963, Ser. No. 290,635, now Patent No. 3,214,442,dated Oct. 26, 1965. Divided and this application Aug. 26, 1965, Ser.No. 482,894

3 Claims. (Cl. 167-33) This application is a divisional of a copendingapplication for Letters Patent, Scr. No. 290,635, filed on June 26,1963, now US. Patent 3,214,442.

The present invention relates to a novel heterosulfur compound and to amethod for its preparation. More particularly, the invention relates tothe preparation of 4,5-dicyano-1,3-dithiole-2-thione oxide and tofungitoxic compositions containing the latter thione oxide as the activeingredient. Still more particularly, the invention is concerned withmethods for protecting agricultural organic and related articles fromattack by microorgan- 1SII1S.

Heretofore, fungicidal compositions containing sulfur compounds as theactive ingredient have been prepared. These, however, have not beenWholly satisfactory, since many do not possess the ability to destroyfungi as well as inhibit fungi spore germination and control bacteriagrowth. It is, therefore, an object of the present invention to preparea sulfur compound useful in a fungicidal composition which overcomes theprior art drawbacks.

To this end, it has been unexpected-1y found that 4,5-dicyano-l,'3-dithiole-2-thione oxide having the formula:

can be readily prepared and incorporated into a composition possessingunusual fungicidal and bactericidal properties. These compositions areparticularly effective in preventing and retarding fungus growth onplant tissues and other organic matter.

According to the present invention, the compound is prepared by theoxidation of 4,5-dicyano-1,3-dithiole-2- thione. The oxidation proceduretakes place in an inert organic solvent, such as acetone, utilizingperacids such as, for instance, peracetic acid or perbonzoic acid. Forexample, an acetone solution containing 4,5-dicyano-'1,-3-dithiole-Z-thione is treated for fifteen minutes with peracetic aciddissolved in acetone. Upon filtration, a red solid material decomposingat 182 C. is obtained. The compound is readily crystallizable fromdioxane or butyl acetate and analyzes as follows:

Calculated for C ON S C, 30; N, 14.0; S 48. Found: C, 29.9; N, 14.2; S48.

In general, it is preferred to incorporate the thione oxide as definedabove in a variety of suitable carriers or diluents. Advantageously, thefungicidal compound is effective in extremely dilute concentrations. Inthis respect, less than 0.0-1 percent is employed to obtain 100 percent-kill of bacteria or fungi. The compositions can be prepared as asolution by dissolving the compound in a Water/ acetone or alcoholmixture. Suitable compositions can also be prepared either as asuspension in a non-solvent, or as a dust. Suspensions or dispersions ofthe thione oxide in a carrier, such as water, are useful in thetreatment of plant foliage. If desired, the fungicidal compound can beconveniently applied to foliage by dissolving the compound in a highlyvolatile liquid carrier, such as dichlorodifluoromethane, maintainedunder pressure. Alternatively, the active compound can be dissolved in aless volatile solvent, such as benzene, and the solution can be furtheradmixed with a highly volatile liquid carrier under ambient pressures.

For some applications, dusts may be required. These can be prepared bymixing the active compounds with materials such as clay, ful'lers earth,bentonite and punice. In this manner, seed can be protected from soilmicroorganisms by incorporating the active compound in a solid carrier,while tumbling seeds with the composition.

As stated above, it is critical that less than 0.01 percent of fungicidecompound be present in the inert carrier. For most purposes, a range offrom 0.001 percent to 0.005 percent is entirely satisfactory.

Advantageously, the compositions of the present invention may includecompatible commercially available dispersing agents for the compound,particularly when it is employed in an aqueous suspension. illustrativeof such dispersing or surface-active agents are the fatty acid esters ofpolyhydric alcohol, the sodium salt of polymerized propyl naphthalene,sulfonic acid and the ethylene oxide condensates of alkylaryl polyether'alcohols. It is a good practice to employ from one to live parts peronehundred parts of fungicide.

The following examples are presented merely by way of illustration andare not to be taken as limitative of the invention. All parts are byweight, unless otherwise stated.

Example 1 TABLE I Percent Inhibition of Fungus Spores in 24 PercentConcentra- Hours tion (T.O.)

lldonoliniafmctigena Stemphylium sarci'nac- Example 2 The compound: T0.is tested against two fungus diseases: anthracnose of cucumberand lateblight of tomato, which is caused by the fungi Collezotrichwn lagenariumand Phytophthora infeslans, respectively.

In these tests, four cucumber plants (Green Profilic) and five tomatoplants (variety Richarcd) are transplanted as seedlings into 6" x jiffyflats. They are interspersed in each flat and when grown to the state oftwo true leaves, they are ready for test use. The compound: T0. isprepared as a 500 p.p.m. and a 100 p.p.m. suspension in a 50/50acetone/water mixture. Sixty (60) parts of the compound are placed in 60parts by volume of acetone and 60 parts by volume of water. Thisconstitutes a 500 p.p.m. suspension. Twenty parts by volume of thissolution are then added to 80 parts of 50/50 acetone and Water diluent.This yields a 100 p.p.m. suspension.

An inoculum containing equal amounts, namely about 50,000 spores permilliliter of freshly cultured colletotrichum which is cultured onpotato dextrose agar, and Phytophthora cultured on sterilized wheatseed, is next prepared.

Two of the 6" x 10" jiffy flats as previously prepared are employed ascontrols and are sprayed with the 50/50 acetone and water solution. Twoflats are additionally sprayed with a 100 p.p.m. solution of the activecompound in 50/50 acetone and water and two additional fiats are sprayedwith a 500 p.p.m. solution of the compound. When the flats are dried,the mixed i-noculum as previously prepared is applied to the flatssprayed with solutions of the active compounds. The so-treated flats aremaintained along with the control at 65 F. and 100% relative humidity topermit the invasion of leaf tissue by fungi organisms for thirty-six toforty-eight hours. Thereafter, the flats are transferred from therelative humidity chamber to the atmosphere and given regular care untilthe disease causes lesions on the foliage.

It is observed that where the flats have been treated with 100 p.p.m.solutions of the active compound, the infested plants are completelyhealthy. However, the flats treated with the 500 p.p.m. solution showherbicidal activity. Therefore, 100 p.p.m. concentration should not beexceeded, since a concentration of 100 p.p.m. gives complete control ofthe fungi infestation.

Example 3 To each of three test tubes are added 9 parts of deionizedwater. The tubes are next closely capped and autoclaved. When sterileand cool, 1 part by volume of a 1000 p.p.m. solution of the compound:T0. is pipettecl eseptically into each tube so as to yield 100 p.p.m.concentration of the compound in the tube.

One drop of a twenty-four hour broth culture of Aerobacter aerogens, agram-negative rod bacterium, is added to each tube. The tubes aremaintained at room temperature for twenty-four hours. A broth comprising10% peptone and 1% dextrose is prepared and 1.1 parts of the latter areadded to each tube. Aseptic conditions are maintained during the latteraddition. The tubes are incubated at C. for twenty-four hours and thenobserved. All tubes lacking turbidity are then subcultured to cleanpeptone dextrose broth and the subcultures are incubated for anadditional forty-eight hours at 30 C. Any subculture lacking turbidityare reported as kill of the organism at the test concentration and theresults are tabulated in Table 11, below.

TABLE II Percent Concentra Percent Kill 0/ tion (T.O.) Aerobacieracrogcm 0.01 (100 pp in 100 0.001 (10 pp m) 0 Example 4 RepeatingExample 2 in every respect, except that a wettable powder is employed inlieu of the acetone/water solution, the wettable powder is formulated asa mixture of parts by weight of the compound: T.O., 22 parts of clay, 5parts of silica, 1 part of carboxymethylcellulose and 2 parts ofalkylaryl polyether alcohol-ethylene oxide condensate, and thereaftermilling the blended mixture to an average particle size of 1.5 microns.The wettable powder is next incorporated into water to form a 70%aqueous solution and is applied to a host plant previously inoculatedfollowing the procedure of Example 2 above. The results are recorded inTable III below.

1 The total number of anthracnose lesions on the primary leaves of 8replicates cucumber plants per treatment.

What is claimed is:

1. A biocidal composition consisting essentially of an inert biocidalcarrier and an effective amount of 4,5-dicyano-l,3-dithiole-2-thioneoxide.

2. A process for the control of fungi which comprises the steps of:applying to a locus containing fungi a fungicidal composition consistingessentially of an inert fungicidal carrier and an effective amount of4,5-dicyano- 1,3-dithiole-2-thione oxide; and, thereafter, eifectingsubstantial control of said fungi.

3. A process for the control of bacteria which comprises the steps of:applying to a locus containing bacteria an antimicrobial compositionconsisting essentially of an inert carrier and an effective amount of4,5-dicyano-1,3- dithiole-Z-thione oxide; and, thereafter, effectingcontrol of said bacteria.

No references cited.

LEWIS GOTTS, Primary Examiner.

S. K. ROSE, Assistant Examiner.

1. A BIOCIDAL COMPOSITION CONSISTING ESSENTIALLY OF AN INERT BIOCIDALCARRIER AND AN EFFECTIVE AMOUNT OF 4, 5-DICYANO-1, 3-DITHIOLE-2-THIONEOXIDE.